Vapor electric device.



F. P. GOPFIN.

VAPOR ELECTRIC DEVICE.

APPLICATION FILED JAN. 25, 1913.

Patented Oct. 14, 1913.

Inventor Francis P. Cofin,

Witnesses:

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FRANCIS P. COFFIN, 0F SCHENECEDADY, NEW YORK, ASSIGNOR T0GENERALELECTRIC 'OGM-P-A-NY, A CORPORACLION OF NEW YORK.

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Specification of -Letters' Patent.

Patented @ct. Ital, 1913..

To all whom it may concern:

Be it known that 1, FRANCIS P. Corrru,

a citizen of the United States,-resident of Schenectady, county'ofSchenectady, State of New York, have invented certain new and usefulImprovements in Vapor Electric Devices, of which't'he'following is aspecification.

The present invention relates to mercury vapor devices and-particularlyto the construction of large, high powered vapor rectifiers having metalcontainers. @ne of the main problems in the operation of these highpowered rectifiers is the maintenance of steadiness in the arc. llndevices as heretofore constructed the cathode spot is apt to temporarilyjump to the metal wall 'of the cathode chamber, especially when mercuryglobules have condensed on the wall, thus causing the arc to betemporarily extinguished, or as it is termed, causing winking of thearc.

In accordance with my invention the metal cathode chamber is insulatedfrom the main arc chamber, and is also provided with a refractoryinsulating ring or lining overlapping with said insulation for confiningthe arc and preventing it from injuring the insulation by its heatingaction and from climbing up the metal surface.

The structural details of the cathode chamber of the rectifier are shownin the sectional view in Figure 1 and the relation of the cathode to theother parts of the rectifier are shown respectively by the side and topView in Figs. 2 and 3.

As shown in Fig. 2 the rectifier consists of a main arc chamber 1 towhich is joined a cathode chamber 2, insulated therefrom as will bedescribed. In the main arc chamber there are anodes 3 and d surroundedby shields 5 and 6 of suitable refractory material such as silica,alumina or the like. Two anodes have been indicated but of course, anynumber of anodes may be used. The cathode chamber communicates with themain arc chamber by means of a throat 7 as clearly shown in Fig. 1. Thisthroat is joined preferably by welding to the wall 8 of the main envelopand also to an annular disk of metal 9. For convenience of welding thepart 9 is recessed near its juncture with its throat 7 to reduce theamount of metal. After the weld has been made a threaded ring 10 ispreferably driven into vthis'rec'ess to which may besecured the lower orhanging section of the throat. To the metal cathode vessel is joinedanother annular disk or fiange 11 through which pass 'a number of bolts12, two of which are shown. These bolts are insulated from the cathodecontainer by a sleeve 13 of fiber or like material. Asbestos molded witha hinder or" a phenol-formaldehyde condensation product is suitable forthis purpose. The bolts are provided with nuts 14 at either end andspring washers 15.

' Interposed between the cathode cup 2 and the flange 9 is an annularsection of insulat-ion...16. The particular insulation illustratedconsists of a ring of porcelain upon each side of which bear pressuredistributing plates 17 and 18. Aluminum washers 'are provided betweenthe plates 17 and 18 and the adjoining metal wall of the con tainer. Asindicated washers of yielding material, such as asbestos and lead, orrubher, are used between the porcelain cylinder 16 and the plates 17 and18. By tightening the nuts 14, a perfectly vacuum-tight seal may bemade. This asbestos may be impregnated with a cementing material so thatwhen hardened the porcelain and the pressure distributing plates may behandled as one unit.

Lining the cathode pot 2 and extending beyond the insulating ring 16 isa refractory lining or cylinder 19 consisting of silica, alumina andsimilar refractory insulating material. It is a function of thisinsulating lining to confine the active surface of the cathode uponwhich the cathode spot plays and thus to prevent wandering of thecathode spot up the side of the metal wall of the cathode pot. Myexperiments have shown that unless such a barrier is provided a cathodespot will soon injure the insulation between the cathode chamber and themain arc chamber. The ring 19 also serves to protect the insulation fromthe direct heating action of the are. It is assisted in this heatshielding function by the lower hanging wall of the throat. I have foundthat if it is attempted to locate this insulation at some distance fromthe active part of the cathode, and thus to prevent its overheating,globules are condensed on the intervening wall. The are is very apt tojump to these globules of mercury causing unsteadiness of the arc anddefeating the very pur ose for which the cathode was insulate If desiredthe ring or wall 19 may be cemented into direct contact with theinsulation 16 but this is not necessary. In the drawing the ring 19 isshown as floating in the mercury, it being forced into contact with theplate 18 by its buoyancy.

The anodes are made vacuum-tight and insulated similarly to the cathode,as indicated in Fig. 2 by seals 20 and 21. The rectifier is started inoperation by drawing an are between the cathode 22 and the rod 23consisting of molybdenum or other metal. This may be done automaticallyby means of a magnet 24 which draws up its plunger and lifts the rod 23drawing the are. The rod 23 is finally drawn up into a graphite sleeve25. The are is transferred to this sleeve which acts as a sustainingelectrode in a well known manner during the operation of the device. Thegraphite sleeve is attached to a metal tube 26, the lower end of whichis indicated in Fig. 1 and to which the plunger mechanism is bolted. Themain chamber 1 of the rectifier is preferably maintained at thepotential of the sustaining anode by electrically connecting it thereto.

A rectifier constructed as above will carry loads of hundreds ofkilowatts continuously.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

chamber, said lining overlapping the insulation separating said chamberfrom the main arc chamber.

2. In a vapor electric high powered rectifier, a main evacuated metalchamber, a mercury cathode, a metal chamber therefor opening into saidmain chamber, vacuumtight insulation between said chambers, and arefractory insulating sleeve interposed between said insulation and theactive surface of the cathode.

3. A vapor electric device comprising communicating evacuated metallicchambers, at least one anode in one of said chambers, and a mercurycathode in the adjoining chamber, a vacuum-tight insulating seal betweensaid chambers at a point removed from said cathode, a barrier ofinsulating material lining the cathode chamber overlapping with saidseal and inclosing the active portion of the cathode and a wall of metalconfining the are.

4:. In a vapor electric device, a main evacuated metal container, acommunicating metal chamber, an easily vaporizable cathode therein,vacuum-tight insulation between said chambers, a sleeve of refractorymaterial confining the active portion of said cathode, and arc-directingmeans pro jecting from said main chamber, and projecting into saidsleeve.

In witness whereof, I have hereunto set my hand this 23rd day of January1913.

' FRANCIS P. COFFIN.

